About 70-80% of early
breast cancer (BC) patients receive adjuvant endocrine
therapy (ET) for at least 5 years. ET includes in the majority of cases the use of
aromatase inhibitors, as upfront or switch strategy, that lead to impaired bone health. Given the high incidence and also the high prevalence of BC,
cancer treatment-induced bone loss (CTIBL) represents the most common long-term adverse event experimented by patients with
hormone receptor positive tumours. CTIBL is responsible for
osteoporosis occurrence and, as a consequence, fragility fractures that may negatively affect quality of life and survival expectancy. As recommended by main international guidelines, BC women on
aromatase inhibitors should be carefully assessed for their fracture risk at baseline and periodically reassessed during adjuvant ET in order to early detect significant worsening in terms of bone health.
Antiresorptive agents, together with adequate intake of
calcium and
vitamin D, should be administered in BC patients during all course of ET, especially in those at high risk of
osteoporotic fractures, as calculated by tools available for clinicians.
Bisphosphonates, such as
zoledronate or
pamidronate, and anti-RANKL antibody,
denosumab, are the two classes of
antiresorptive drugs used in clinical practice with similar efficacy in preventing bone loss induced by
aromatase inhibitor therapy. The choice between them, in the absence of direct comparison, should be based on patients' preference and compliance; the different safety profile is mainly related to the route of administration, although both types of drugs are manageable with due care, since most of the adverse events are predictable and preventable. Despite advances in management of CTIBL, several issues such as the optimal time of starting
antiresorptive agents and the
duration of treatment remain unanswered. Future clinical trials as well as increased awareness of bone health are needed to improve prevention, assessment and treatment of CTIBL in these long-term survivor patients.